Type Ia Supernovae and the Hubble Constant

The focus of this review is the work that has been done during the 1990s on using Type Ia supernovae (SNe Ia) to measure the Hubble constant ($H_0$). SNe Ia are well suited for measuring $H_0$. A straightforward maximum-light color criterion can weed out the minority of observed events that are either intrinsically subluminous or substantially extinguished by dust, leaving a majority subsample that has observational absolute-magnitude dispersions of less than $\sigma_{obs}(M_B) \simeq \sigma_{obs}(M_V) \simeq 0.3$ mag. Correlations between absolute magnitude and one or more distance-independent SN Ia or parent-galaxy observables can be used to further standardize the absolute magnitudes to better than 0.2 mag. The absolute magnitudes can be calibrated in two independent ways --- empirically, using Cepheid-based distances to parent galaxies of SNe Ia, and physically, by light curve and spectrum fitting. At present the empirical and physical calibrations are in agreement at $M_B \simeq M_V \simeq -19.4$ or -19.5. Various ways that have been used to match Cepheid-calibrated SNe Ia or physical models to SNe Ia that have been observed out in the Hubble flow have given values of $H_0$ distributed throughout the range 54 to 67 km/s Mpc$^{-1}$. Astronomers who want a consensus value of $H_0$ from SNe Ia with conservative errors could, for now, use $60 \pm 10$ km/s Mpc^{-1}$.Comment: 46 pages. Hard copies of figures, all from the published literature, can be obtained from the author. With permission, from the Annual Review of Astronomy and Astrophysics, Volume 36, copyright 1998, by Annual Review

An automated, broad-based, near real-time public health surveillance system using presentations to hospital Emergency Departments in New South Wales, Australia

BACKGROUND: In a climate of concern over bioterrorism threats and emergent diseases, public health authorities are trialling more timely surveillance systems. The 2003 Rugby World Cup (RWC) provided an opportunity to test the viability of a near real-time syndromic surveillance system in metropolitan Sydney, Australia. We describe the development and early results of this largely automated system that used data routinely collected in Emergency Departments (EDs). METHODS: Twelve of 49 EDs in the Sydney metropolitan area automatically transmitted surveillance data from their existing information systems to a central database in near real-time. Information captured for each ED visit included patient demographic details, presenting problem and nursing assessment entered as free-text at triage time, physician-assigned provisional diagnosis codes, and status at departure from the ED. Both diagnoses from the EDs and triage text were used to assign syndrome categories. The text information was automatically classified into one or more of 26 syndrome categories using automated "naïve Bayes" text categorisation techniques. Automated processes were used to analyse both diagnosis and free text-based syndrome data and to produce web-based statistical summaries for daily review. An adjusted cumulative sum (cusum) was used to assess the statistical significance of trends. RESULTS: During the RWC the system did not identify any major public health threats associated with the tournament, mass gatherings or the influx of visitors. This was consistent with evidence from other sources, although two known outbreaks were already in progress before the tournament. Limited baseline in early monitoring prevented the system from automatically identifying these ongoing outbreaks. Data capture was invisible to clinical staff in EDs and did not add to their workload. CONCLUSION: We have demonstrated the feasibility and potential utility of syndromic surveillance using routinely collected data from ED information systems. Key features of our system are its nil impact on clinical staff, and its use of statistical methods to assign syndrome categories based on clinical free text information. The system is ongoing, and has expanded to cover 30 EDs. Results of formal evaluations of both the technical efficiency and the public health impacts of the system will be described subsequently

Microvertebrates preserved in mammal burrows from the Holocene of the Argentine Pampas: a taphonomic and paleoecological approach

Microvertebrates are a major component of many assemblages recovered from the Quaternary of the Argentine Pampas. The main goal of this paper is to analyse the taphonomic history of a Holocene microfossil bonebed, recovered from the infilling of a burrow. Evidences suggest the plains vizcacha Lagostomus maximus as the putative producer of the burrow. The assemblage includes individuals belonging to different taxa of mammals (marsupials and rodents) and reptiles (snakes). Taphonomic features suggest that the accumulation inside the burrow was related to flooding processes in the plain. The burrow was a natural trap that favoured the accumulation and preservation of remains corresponding to individuals from different sources. According to the taphonomic evidence, some individuals (Lagostomus maximus, Lestodelphys halli and Serpentes indet.) died inside the burrow, whereas others (Microcavia australis, Reithrodon auritus and Ctenomys sp.) died outside the burrow, and after a time of being exposed on the surface their remains were transported by surface run-offs into the burrow. The record of Lestodelphys halli and Serpentes indet. in the burrow produced by Lagostomus maximus could be related to a circumstantial use. Mammal burrows are a significant taphonomic mode for the late Cenozoic of the Argentine Pampas

Teaching About Health Care Disparities in the Clinical Setting

Clinical teachers often observe interactions that may contribute to health care disparities, yet may hesitate to teach about them. A pedagogical model could help faculty structure teaching about health care disparities in the clinical setting, but to our knowledge, none have been adapted for this purpose. In this paper, we adapt an established model, Time-Effective Strategies for Teaching (TEST), to the teaching of health care disparities. We use several case scenarios to illustrate the core components of the model: diagnose the learner, teach rapidly to the learner’s need, and provide feedback. The TEST model is straightforward, easy to use, and enables the incorporation of teaching about health care disparities into routine clinical teaching

Biodiversity, traditional medicine and public health: where do they meet?

Given the increased use of traditional medicines, possibilities that would ensure its successful integration into a public health framework should be explored. This paper discusses some of the links between biodiversity and traditional medicine, and addresses their implications to public health. We explore the importance of biodiversity and ecosystem services to global and human health, the risks which human impacts on ecosystems and biodiversity present to human health and welfare

The temporal dynamics and infectiousness of subpatent Plasmodium falciparum infections in relation to parasite density

Malaria infections occurring below the limit of detection of standard diagnostics are common in all endemic settings. However, key questions remain surrounding their contribution to sustaining transmission and whether they need to be detected and targeted to achieve malaria elimination. In this study we analyse a range of malaria datasets to quantify the density, detectability, course of infection and infectiousness of subpatent infections. Asymptomatically infected individuals have lower parasite densities on average in low transmission settings compared to individuals in higher transmission settings. In cohort studies, subpatent infections are found to be predictive of future periods of patent infection and in membrane feeding studies, individuals infected with subpatent asexual parasite densities are found to be approximately a third as infectious to mosquitoes as individuals with patent (asexual parasite) infection. These results indicate that subpatent infections contribute to the infectious reservoir, may be long lasting, and require more sensitive diagnostics to detect them in lower transmission settings